True, though it depends on energy mix and location, and all day on weekends are also often similar. If any of your local electricity providers have a variable time of use tariff, that's a pretty good guide to when the cheapest (and often, but not always, the greenest) electricity is available.
Some EVs can automatically charge at these times, and sometimes you get discounts for charging at these times, but you can also usually just set a timer on your charger.
https://www.oeb.ca/consumer-information-and-protection/elect...
For example the above suggests it's usually nighttime, but weekends and statutory holidays are also good.
As an aside, I wonder how much money an economy could save by having a new "cheap electricity holiday' which chooses one or two days a year that they announce a month in advance as national holidays when an extreme weather event is predicted.